Sarcoids
Nathan Voris, DVM
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“It’s not a tumor!” I encourage everyone reading this to say the previous sentence aloud, using their best Arnold Schwarzenegger (Kindergarten Cop) accent. I guarantee you will make the person next to you laugh.
All joking aside, sarcoids are tumors. In fact, sarcoids are the most common skin tumor of the horse, mule and donkey. Sarcoids are benign tumors, but are locally invasive which can make them difficult to treat. An additional feature that makes them difficult to treat is their origin. Sarcoids appear when a horse suffers some sort of skin damage and then is infected with the Bovine Papillomavirus. Flies have been implicated as a primary vector of spreading the virus to horses.
The clinical appearance of a sarcoid varies. There are flat sarcoids that look a lot like ringworm; verrucous sarcoids that look like warts; and fibroblastic sarcoids which appear as nodules or ulcerated masses.
There are many treatments available, including cryotherapy (freezing), hyperthermic treatment, intra-lesional and/or topical chemotherapy, immunotherapy, radiation, surgical removal and combinations of the aforementioned modalities. Unfortunately, there is no single treatment protocol that has shown great advantage in efficacy over the other. Oftentimes, multiple modalities, over an extended period of time may need to be implemented to achieve resolution. The choice of treatment modality will vary with the type of sarcoid, the location of the tumor and its size. As with any disease, treating sarcoids aggressively as soon as they are noticed will increase the chance of successful treatment.